Monitoring bald eagles using lists of nests: Response to Watts and Duerr

Journal of Wildlife Management
By: , and 



The post-delisting monitoring plan for bald eagles (Haliaeetus leucocephalus) roposed use of a dual-frame sample design, in which sampling of known nest sites in combination with additional area-based sampling is used to estimate total number of nesting bald eagle pairs. Watts and Duerr (2010) used data from repeated observations of bald eagle nests in Virginia, USA to estimate a nest turnover rate and used this rate to simulate decline in number of occupied nests in list nests over time. Results of Watts and Duerr suggest that, given the rates of loss of nests from the list of known nest sites in Virginia, the list information will be of little value to sampling unless lists are constantly updated. Those authors criticize the plan for not placing sufficient emphasis on updating and maintaining lists of bald eagle nests. Watts and Duerr's metric of turnover rate does not distinguish detectability or temporary nonuse of nests from permanent loss of nests and likely overestimates turnover rate. We describe a multi-state capture–recapture model that allows appropriate estimation of rates of loss of nests, and we use the model to estimate rates of loss from a sample of nests from Maine, USA. The post-delisting monitoring plan addresses the need to maintain and update the lists of nests, and we show that dual frame sampling is an effective approach for sampling nesting bald eagle populations.
Publication type Article
Publication Subtype Journal Article
Title Monitoring bald eagles using lists of nests: Response to Watts and Duerr
Series title Journal of Wildlife Management
DOI 10.1002/jwmg.84
Volume 75
Issue 3
Year Published 2011
Language English
Publisher The Wildlife Society
Publisher location Bethesda, MD
Contributing office(s) Patuxent Wildlife Research Center
Description 4 p.
First page 509
Last page 512
Country United States
State Virginia
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